Color chain to distinguish calmodulin from its target peptide.
Display as ribbons or cartoon
to show the largely a-helical structure of both proteins.
Note how calmodulin
(blue) wraps around the target peptide (green).

Select hetero-ligand, display as spacefill, & color CPK to visualize Ca++. Question: How many Ca++ ions are bound to calmodulin?
Drag the image, and observe the helix-loop-helix motif of each Ca++
binding site.

Type into the command line selectmet*a,
enter, and then change display to spacefill,
with color CPK, to view the cluster of
methionine residues that forms a hydrophobic pocket at each end of calmodulin.
Select leu299
and change its display to view the position of a conserved hydrophobic residue
in the target protein. This residue, which may be either Trp or Leu, is
essential for sensitivity of some kinases to calmodulin.

Now, to get a clearer view of one Ca++
binding site, select
all, and then hideselected.
Type
into the command line select1-40a, enter, and display as ribbons.
Select
ca1 (calcium #1) & display as spacefill.
Enter select 20-26a, display as ball & stick, and color CPK. Hold down the shift while left-dragging to zoom in.Identify
amino acids that
interact with Ca++. (Hint: May include anionic amino acids above).
Question:
What atoms of
what chemical groups interact with Ca++?